Modern land-based (“onshore”) wind turbines in the megawatt range have grown increasingly more powerful and correspondingly larger. The towers that support the power generating components of these wind turbines can exceed well over 60 meters in height. For example, GE Wind Energy offers a 2.5 MW wind turbine with standard available hub heights of 75 meters, 85 meters, and 100 meters. Larger wind turbines with hub heights in excess of 100 meters are becoming more common.
The tower structures of these large wind turbines can be massive, particularly at the base section of the tower wherein a significant footprint and weight are needed to achieve design tower support criteria. In this regard, the towers are becoming increasing more expensive to manufacture, transport, and erect. In many instances, the dimensions of the lower tower sections are limiting factors in site selection and transport of the tower sections to the site. For example, the tower sections cannot exceed the local jurisdiction's maximum size and weight limits for rail and truck transport.
Accordingly, the industry would benefit from an improved tower structure that is capable of supporting larger turbines at significant hub heights without the size, weight, and cost issues of conventional towers.